refactor(武器系统): 重构火山武器和火扫弹攻击机制

移除火扫弹的独立脚本和火罐效果，改为直接在子弹中实现
火山武器改为三段伤害机制并调整基础伤害值
添加子弹基础伤害乘数数组支持多段伤害
更新相关场景和资源配置以匹配新机制

scripts/Statemachine/BulletBase.gd

@@ -31,6 +31,8 @@ var isChildSplit: bool = false
 var isChildRefract: bool = false
 var initialSpeed: float = 0
 var originalDamage: float = 0
+var damageMultiplier: Array[float] = [1.0]
+var usingDamageMultiplier: int = 0
 
 func _ready():
 	initialSpeed = speed
@@ -84,6 +86,8 @@ func _physics_process(_delta: float) -> void:
 	else:
 		tryDestroy()
 
+func getDamage():
+	return originalDamage * damageMultiplier[usingDamageMultiplier]
 func hit(target: Node):
 	var entity: EntityBase = EntityTool.fromHurtbox(target)
 	if !entity || !launcher: return